Spring mounting for keys



Feb. 7, 1967 w. STUIBER ETAL 3,302,377

SPRING MOUNTING FOR KEYS Filed April 15, 1965 5 Sheets-Sheet l BY w J ATTORNEY Feb. 7, 1967 w. STUIBER ETAL SPRING MOUNTING FOR KEYS Fil ed April 15 5 Sheets-Sheet 2 ATTORNEY Feb. 7, 1967 w. STUIBER ETAL SPRING MOUNTING FOR KEYS 3 Sheets-Sheet 3 Filed April 15, 1965 ATTORNEY United States Patent 3,302,877 SPRING MOUNTHNG FOR KEYS Walter Stnibcr, Stein, near Nurnberg, and Herbert Decker, Nurnberg, Germany, assignors to Max Grundig, Furtlr, Bavaria, German Filed Apr. 13, 1965, Ser. No. 447,687 Claims priority, application Germany, Apr. 21, 1964, G 40,403 19 Claims. (Cl. 235-145) The present invention relates to a spring mounting tor keys, and more particularly to an arrangement in which the keys of the key-board of a business machine, such as a typewriter, calculator, or accounting machine, are loaded by a spring to oppose the pressure exerted by the fingers of the operator on the keys.

The springs acting on key levers to return the keys after actuation, should exert the same resilient force on all keys of the keyboard. Furthermore, the spring should return the key levers rapidly to the position of rest, and be adjustable to the different -forces exerted by the fingers of different operators on the keys.

It is very desirable that the spring force is not constant during the entire movement of an actuated key from the position of rest to the actuated position, but that the spring force increases during such movement of the key in order to indicate to the operator that the type action, or corresponding device has been actuated by the key. After actuation of the type action, the spring :force resisting the movement of the key should be further increased so that the key is not depressed after the corresponding type action has been actuated. This could be accomplished by a fixed stop blocking movement of the key lever, but this solution is undesirable, because the movement of the fingers of the operator is suddenly stopped which causes fatigue of the operator, and even injury to the finger tips.

On the other hand, if the spring force is substantially increased after actuation of the type action, the return movement of the key lever is rapidly started and carried out, which has a favorable influence on the typing speed.

It has been proposed to use a first spring for resisting the first part of the movement of the key, and an additional spring which is located in the path of movement of the key lever and engages the same after the respective type action has been actuated by the key. The disadvantage of this construction is that two springs are required for each key lever which not only results in a difiicult and expensive assembly operation, but also causes additional friction fiorces which influence the return movement of the key lever to its position of rest.

it is one object of the invention to overcome the disadvantages of prior art constructions serving the purpose of biasing the keys of a keyboard operated machine, and to provide a device of extremely simple construction serving this purpose.

Another object of the invention is to bias the key means of a keyboard operated machine by a single spring, and to vary the spring force of the single spring in such a manner that it is greater after actuation of the corresponding type action.

Another object of the invention is to provide a common spring for a plurality of. key means, and to block the resilient deformation of the spring when the key means arrive at a certain position so that the effective spring force is increased.

With these objects in view, the present invention relates to spring means acting on the keys of a keyboard. One embodiment of the invention com uprises movable key means; spring means resisting the movement of the key means; and control means engageable with the spring means for increasing the spring force exerted by the same on the key means during movement of the key means.

The control means are manually operable and settable between a plurality of control positions for differently increasing the spring force of the spring means.

A preferred embodiment of the invention comprises key means operable to move to an actuated position; spring means having a first end portion abutting the key means and a second end portion abutting supporting means so that a third intermediate portion of the spring means is displaced during movement of the key means to the actuated position. Control means engage the displaced portion of the spring means and limit movement of the same, preferably in different positions, so that a greater spring force acts on the key means after engagement of the third portion by the control means.

When the invention is applied to a row of key means, a comb-shaped leaf spring is used which has a plurality of resilient pron-gs which respectively abut the key levers. Upon actuation of any key, the respective pron-g is bent, and a blocking portion of the control means blocks the bent portion of the respective prong and thereby increases the spring force exerted on the actuated key.

The control means can be turned between diiferent control positions in which the blocking portion thereof is spaced different distances from the prongs so that in each control position, the spring force of the respective prong is differently increased.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a fragmentary side elevation, partially in section, and illustrating an embodiment of the invention in a position of rest;

FIG. 2 is a side elevation corresponding to FIG. 1 and illustrating a key in actuated position;

FIG. 3 is a side elevation corresponding to FIG. 1 but illustrating another operational position of the device;

FIG. 4 is a side elevation corresponding to FIG. 1 but illustrating a third operational position of the device;

FIG. 5 is a fragmentary front view of a comb-shaped leaf spring used in the device;

FIG. 6 is a fragmentary perspective view illustrating a modification of the construction; and

FIG. 7 is a fragmentary plan, partially in section, and illustrating control means according to the invention.

Referring now to the drawings, a row of key means 2 including key levers 2a is mounted in the usual manner on the frame of a keyboard operated machine, such as a typewriter or other business machine. Only one key means 2 is visible in FIGS. 1 to 4, the other key means "being covered by the illustrated key means.

All key levers 2a have portions guided in slots of a stationary supporting means 1 which is an elongated U- shaped member extending parallel to the row of key means 2. Each key lever has a recess 6 terminating in a narrow slot portion 6a into which the end portion 4a of a prong 4 of a comb-shaped leaf spring 3 projects. Leaf spring 3 is best seen in FIG. 5, and has a longitudinally extending back portion 3a extending parallel to the rows of keys, and projecting tongues 3 located in cutouts 1a of a leg portion of supporting means 1. In the normal position of rest of key means 2 illustrated in FIG. 1, the distance between recess 6 and cutout 1a is less than the transverse width of the comb-shaped leaf spring 3 so that prongs 4 are bent and the leaf spring is pretensioned to urge the key means to the position of rest. It is evident that upon depression of key means 2, the respective prong 4 of the comb-shaped leaf spring 3 will be bent to a smaller radius of curvature as shown in FIG. 2.

In the embodiment of FIG. 1 and FIG. 5, prong end portions 4a have cutouts 5 forming lateral portions which are located on opposite sides of the respective key lever when the prong end portion 4a is inserted into slot 6a. In this manner, lateral displacement of the prongs in relation to the respective key levers is prevented, while the narrow slot 6a assures a movement of the end portion 4a of the prong with the actuated key lever.

In the modified embodiment shown in FIG. 6, key lever 2 has a hook-shaped projection 8, and the end portion 4a of prong 4' is formed with a rectangular cutout 7 receiving projection 8, while the free end of end portion 4a is located in a slot 9 of the key lever. The lateral portions located on opposite sides of cutout 7 and of projection 8 prevent a lateral displacement of the prong 4 relative to the respective key lever 2.

Control means are provided for controlling the displacement of the bent prongs 4. A U-shaped control member 12 has a pair of legs mounted for turning movement on a pair of pivot screws 10 secured to supporting means 10a. One pivot pin engages a bore in a leg 13, and the other pivot pin engages a slot 11 in the other leg 13 which has another cutout 18 provided with catch projections 21 forming recesses for receiving a pin 19 which is secured to supporting means 10a, as best seen in FIG. 7. A spring 14 connects pin 19 with a projecting hook portion of the respective leg 13 so that the arresting catch portions 21 and the intermediate recesses are urged against pin 19. Slot 11 permits such slight displacement of control means 12.

The central yoke portion of control member 12 is provided with a blocking plate 15 which projects toward the bent intermediate portion of the prongs 4. Blocking portion 15 is formed with cutouts forming projections 16 which respectively abut prongs 4 of the comb-shaped leaf spring. However, the cutouts may be omitted, and a continuous edge provided at the free end of blocking portion 15.

Control member 17 has a manually operable handle 17 which projects from the casing of the machine, not shown, and can be turned by an operator in the direction of the arrow at from the position shown in FIG. 2 to the positions shown in FIGS. 3 and 4 in which stop pin 19 is located in different recesses between catch projections 21. When control means 12, 13, 15, 17 is turned between the control positions illustrated in FIGS. 2 to 4, the free edge of the blocking portion 15 is moved toward the prongs 4. In the position of FIG. 1, when stop pin 19 is located in the uppermost recess, the free edge of blocking portion 15 is spaced from the prongs 4 in the position of rest of the key 2 shown in FIG. 1, and in the actuated position of the key, the deformed and strongly bent prong 4 associated with the respective key, just touches the edge of blocking portion 15 so that the spring force of the prong is not influenced.

When the control means is turned in the direction of the arrow a to the control position shown in FIG. 3, blocking portion 15 has been moved farther toward the prongs 4. However, the prongs do not engage the free edge of blocking portion 15 in the position of rest schernatically indicated for key 2 in chain lines. FIG. 3 shows the actuated position of a key 2 in which the respective prong 4 has been deformed, but prong 4 could not assume a uniformly curved position since an intermediate portion thereof is blocked by the free edge of blocking portion 15 so that, in fact, only the portion of the prong 4 between blocking portion 15 and recess 6 exerts a resilient force on key lever 2a. Consequently, the spring force opposing the movement of key 2 to the actuated position, is suddenly and substantially increased at the moment in which the respective prong 4 abuts the free edge of blocking portion 15.

In the position of FIG. 4, the control means has been farther turned in counterclockwise direction so that the blocking portion 15 is now in a blocking position in which the distance between its free edge and the prongs 4 in the position of rest shown in FIGv 4, is decreased. Consequently, upon actuation of the key, the bent corresponding prong 4 will be sooner engaged and blocked by the free edge of blocking portion 15, and the spring force opposing the movement of the key Will be even more increased as compared with the control position shown in FIG. 3.

It will be seen that the construction of the present invention permits in a very simple manner to increase the spring force of a spring which opposes the movement of the key means to the actuated position, and that the spring force can be increased differently in accordance with the requirements of different operators. The same spring serves the purpose of returning the key levers to the position of rest, and for indicating to the operator by suddenly increased opposing resilient force that the key has completed its task of actuating a type action, or corresponding device of a business machine.

The comb-shaped leaf spring may longitudinally extend for the entire length of the row of keys, but it may be preferred to provide a comb-shaped leaf spring for every eight keys so that each leaf spring has eight prongs respectively cooperating with eight key levers.

In keyboards of typewriters, it is advantageous to make the width B of the prong end portions 4a, see FIG. 5, different for different rows of keys. Although generally speaking the distance of travel of all key means 2 is the same for all rows of keys of a typewriter, the lengths of the key levers of the several rows of key means are different, so that the prongs 4 acting on the keys of the upper rows have to provide a smaller opposing force, and are consequently narrower than the prongs acting on the key levers of the keys of the lower rows.

The illustrated embodiment of FIG. 7 in which the blocking portion 15 has a plurality of separate tongues 16 respectively cooperating with prongs 4, has the advantage that it is possible to break off or cut off tongues 16 where the blocking of a resilient prong 4 is not desired, for example where the respective key causes a function of the typewriter, such as shifting from upper case position to lower case position, or causing a carriage return.

The construction of the present invention is not only extremely simple and reliable in operation, but has the advantage that the spring force acting on the keys during the first part of the movement of the same, is in no way influenced by the adjustment of the spring force during the second part of the movement. On one hand, this facilitates the operation of the control means, and on the other hand, it has the advantageous result that the resilient force opposing the movement of the keys out of the initial position of rest remains the same irrespective of the adjustment of the control means. Only after a resilient prong 4 has been blocked by the blocking portion 15 of the control means, the spring force is changed and increased.

The assembly of the device is extremely simple, since after insertion of the prong end portions 4a int-o recesses 6 and slots 60, the tongues 3 are snapped into the corresponding cutouts 1a of the supporting means 1. These cutouts need not be provided in the member which guides the key levers, but may be provided in another support.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of keyboard operated machines diifering from the types described above.

While the invention has been illustrated and described as embodied in a spring loading arrangement for the keys of a business machine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a keyboard operated machine, in combination, key means operable to move to an actuated position; supporting means; spring means having a first portion abutting said key means, a second portion abutting said supporting means, and a third portion displaced when said key means move toward said actuating position and displace said first portion; and control means for engaging said displaced third portion after a predetermined movement of said key means and deactivating a portion of said spring means intermediate said second and third portions thereof so that a greater spring force acts on said key means after engagement of said third portion by said control means.

2. In a keyboard operated machine, in combination, key means operable to move to an actuated position; supporting means; spring means having a first portion abutting said key means, a second portion abutting said supporting means, and a third portion displaced when said key means move toward said actuating position and displace said first portion; and manually opera-ted control means settable to a plurality of control positions for engaging said displaced third portion in different displaced positions and for deactivating a portion of said spring means intermediate said second and third portions thereof bylimiting movement of said third portion so that a greater spring force acts on said key means after engagement of said third portion by said control means, said greater spring force being different for different control positions of said control means.

3. In a keyboard operated machine, in combination, key means operable to move to an actuated position; supporting means; leaf spring means having a first end portion abutting said key means, a second end portion abutting said supporting means, and a third intermediate portion dis-placed along a given path when said key means move toward said actuating position and displace said first end portion; and control meanslocated in the path of said third portion for engaging said third portion after the latter is displaced in predetermined amount and for limiting movement of the same thereby deactivating a portion of said leaf spring so that a greater spring force acts on said key means after engagement of said third portion by said control means.

4. In a keyboard operated machine, in combination, key means operable to move between a position of rest and an actuated position; supporting means; a leaf spring having a first end portion abutting said keys means, a second end portion abutting said supporting means, and a third intermediate portion displaced along a given path when said key means moves with said first end portion to said actuated position; and a manually setta-ble control means mounted on said supporting means for turning movement between a plurality of control positions and having a blocking portion located in the path of said third portion and spaced in said control positions different distances from said third portion while said key means is in said position of rest so that said blocking portion blocks movement of said third portion in different displaced positions, said blocking portion engaging said third portion in said different displaced positions thereby deactivating a portion of said spring whereby different spring forces act on said key means, said different spring forces being greater than the spring force acting on said key means before blocking of said third portion.

5. In a keyboard operated machine, in combination, key means including a key lever having a recess and being operable to move between a postiion of rest and an actuated position; supporting means; a leaf spring having a first end portion located in said recess abutting said key lever, a second end portion abutting said supporting means, and a third intermediate portion displaced along a given path when said key means moves with said key lever and said first end portion to said actuated position; and a manually settable control means mounted on said supporting means for turning movement between a plurality of control positions and having a blocking portion located in the path of said-third portion and spaced in said control positions different distances from said third portion while said key means is in said position of rest so that said blocking portion blocks movement of said third portion in different displaced positions, said blocking portion engaging said third portion in said different displaced positions thereby deactivating a portion of said spring whereby different spring forces act on said key means, said different spring forces being greater than the spring force acting on said key means before blocking of said third portion.

6. In a keyboard operated machine, in combination, key means including a key lever having a recess with a narrow slot portion and being operable to move between a position-of rest and an actuated position; supporting means; a leaf spring having a first end portion located in said slot portion abutting said key lever and including two spaced ilateral parts located on opposite sides of said key lever, a second end portion abutting said supporting means, and a third intermediate portion displaced along a given path when said key means moves with said key lever and said first end portion to said actuated position; and a manually settable control means mounted on said supporting means for turning movement between a plurality of control positions and having a blocking portion located in the path of said third portion and spaced in said control positions different distances from said third portion while said key means is in said position of rest so that said blocking portion blocks movement of said third portion in different displaced positions, said blocking portion engaging said third portion in said different displaced positions thereby deactivating a portion of said spring whereby different spring forces act on said key means,

said different spring forces being greater than the spring force acting on said key means before blocking of said third portion.

7. In a keyboard operated machine, in combination, key means including a key lever having a recess and a projection, and being operable to move between a position of rest and an actuated position; supporting means; a leaf spring having a first end portion located in said recess abutting said key lever, and having a cutout movably receiving said projection, a second end portion abutting said supporting means, and a third intermediate portion displaced along a given path when said key means moves with said key lever and said first end portion to said actuated position; and a manually sett able control means mounted on said supporting means for turning movement between a plurality of control positions and having a blocking portion located in the path of said third portion and spaced in said control positions different distances from said third portion while said key means is in said position of rest so that said blocking portion blocks movement of said third portion in different displaced positions, said blocking portion engaging said third portion in said different displaced positions thereby deactivating a portion of said spring whereby different spring forces act on said key means, said different spring forces being greater than the spring force acting on said key means before blocking of said third portion.

8. In a keyboard operated machine, in combination, key means operable to move between a position of rest and an actuated position; supporting means; a spring having a first end portion abutting said key means, a sec-ond end portion abutting said supporting means, and a third intermediate portion displaced along a given path when said key means moves with said first end portion to said actuated position; a manually settable control means movable between a plurality of control positions and having a blocking portion located in the path of said third portion and spaced in said control positions different distances from said third portion while said key means is in said position of rest so that said blocking portion blocks movement of said third portion in different displaced positions, said blocking portion engaging said third portion in said different displaced positions thereby deactivating a portion of said spring whereby different spring forces act on said key means, said different spring forces being greater than the spring force acting on said key means before blocking of said third portion; means for mounting said control means on said supporting means for turning movement between said control positions and for translatory movement in the direction of displacement of said third portion; resilient means connecting said control means with said supporting means so that said control means can be resiliently displaced; and catch means engaged by said control means under the action of said resilient means for arresting said control means in said control positions.

9. In a keyboard operated machine, in combination, a plurality of key means arranged in a row, each key means being operable between a position of rest and an actuated position, and including a key lever; supporting means; a comb-shaped leaf spring having an elongated back portion extending parallel to said row abutting said supporting means, and a plurality of resilient prongs respectively abutting said key levers so that said prongs are bent, respectively, during movement of said key means to said actuated position whereby a portion of each bent prong is displaced; and control means manually settable between a plurality of control positions and including an elongated blocking portion parallel with said row and being spaced in said control positions different distances from said prongs of said leaf spring while said key means are in said position of rest so that said blocking portion blocks in said control positions bending movement of any prong whose key means moves to said actuated position in differently deformed positions where-by different spring forces act on said key means, said different spring forces being greater than the spring force acting on each key means before blocking by said blocking portion.

10. A keyboard operated machine as set forth in claim 9 wherein said leaf spring is curved and pretensioned in said position of rest, and wherein each prong displaced by the corresponding key lever is bent to a smaller radius of curvature until engaged by said blocking portion.

11. A keyboard operated machine as set forth in claim 9 wherein each key lever has a slot and a projection, and wherein each prong has a free end formed with a cutout and located in said slot with said projection of said key ilever located in said cutout.

12. A keyboard operated machine as set forth in claim 11 wherein said control means includes a U-shaped control member having a pair of legs mounted for turning movement on said supporting means, and a yoke portion extending parallel to said row and having a projecting plate forming said blocking portion so that said prongs are engaged and blocked by the free edge of said projecting blocking portion,

13. A keyboard operated machine as set forth in claim 12 wherein said free edge of said projecting blocking portion is formed with cutouts forming tongues respectively having the same width as said prongs, being spaced the I same distance as said prongs, and cooperating with said prongs, respectively, to block movement of bent prongs.

14. A keyboard operated machine as set forth in claim 9 wherein said prongs have different widths and produce different spring forces opposing the movement of the respective correlated key levers.

15. A key-board operated machine as set forth in claim 9 and including catch means for arresting said control means in said control positions.

16. A keyboard operated machine as set forth in claim 9 wherein said control means is mounted on said supporting means for translatory movement; resilient means connecting said supporting means with said control means; andarresting means including a plurality of catch projections and intermediate recesses, and a stop on said control means cooperating with said recesses and urged by said resilient means into one of said recesses in each of said control positions of said control means.

17. In a keyboard operated machine, in combination,

key means movable between a pair of end positions and through an intermediate position; spring means for resisting movement of said key means from one of said pair of positions to the other thereof, said spring means including a first and a second spring portion; and means engaging said spring means for deactivating said second spring portion thereof when said key means reaches said intermediate position, said spring means being constructed and arranged to exert a greater spring force on said key means when said second portion is deactivated so that said spring means resists movement of said key means from said intermediate to said other position thereof to a greater degree than movement of the latter from said one to said intermediate position thereof.

18. In a keyboard operated machine, in combination, key means movable between a pair of end positions and through an intermediate position; leaf spring means for resisting movement of said key means; and control means for engaging one portion of said leaf spring means for deactivating a second portion thereof when said key means reaches said intermediate position thereof so as to automatically substantially change the force with which said spring means acts on said key means.

19. In a keyboard operated machine, in combination, key means movable between a pair of end positions and through an intermediate position; spring means for resisting movement of said key means; and control means engaging said spring means when said key means reaches said intermediate position thereof for automatically deactivating a portion of said spring means thereby to increase the force exerted by said spring means on said key means.

References Cited by the Examiner FOREIGN PATENTS 10/1941 Great Britain. 12/1942 Great Britain. 

2. IN A KEYBOARD OPERATED MACHINE, IN COMBINATION, KEY MEANS OPERABLE TO MOVE TO AN ACTUATED POSITION; SUPPORTING MEANS; SPRING MEANS HAVING A FIRST PORTION ABUTTING SAID KEY MEANS, A SECOND PORTION ABUTTING SAID SUPPORTING MEANS, AND A THIRD PORTION DISPLACED WHEN SAID KEY MEANS MOVE TOWARD SAID ACTUATING POSITION AND DISPLACE SAID FIRST PORTION; AND MANUALLY OPERATED CONTROL MEANS SETTABLE TO A PLURALITY OF CONTROL POSITIONS FOR ENGAGING SAID DISPLACED THIRD PORTION IN DIFFERENT DISPLACED POSITIONS AND FOR DEACTIVATING A PORTION OF SAID SPRING MEANS INTERMEDIATE SAID SECOND AND THIRD PORTIONS THEREOF BY LIMITING MOVEMENT OF SAID THIRD PORTION SO THAT A GREATER SPRING FORCE ACTS ON SAID KEY MEANS AFTER ENGAGEMENT OF SAID THIRD PORTION BY SAID CONTROL MEANS, SAID GREATER SPRING FORCE BEING DIFFERENT FOR DIFFERENT CONTROL POSITIONS OF SAID CONTROL MEANS. 